Nicotine is the addictive substance found in tobacco plants. Benzoic acid can also be naturally present in crops, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and clinical research recommend that glycerin and propylene glycol irritate the lining of the lungs. One small clinical examine from 2018 that discovered that the compounds changed vapers’ sputum—the mucosal lining that covers the interior respiratory tract—to precise completely different immune proteins. Some of those protein adjustments have been linked to asthma. Sign up for our Health Tip of the Day e-newsletter, and obtain daily tips that will allow you to reside your healthiest life.